There are two main types of strokes:
The table below shows the basic differences:
| Ischaemic | Haemorrhagic | |
|---|---|---|
| Essential problem | 'Blockage' in the blood vessel stops blood flow | Blood vessel 'bursts' leading to reduction in blood flow |
| Proportion of strokes | 85% | 15% |
| Subtypes | Thrombotic stroke | |
| • thrombosis from large vessels e.g. carotidEmbolic stroke | ||
| • usually a blood clot but fat, air or clumps of bacteria may act as an embolus | ||
| • atrial fibrillation is an important cause of emboli forming in the heart | Intracerebral haemorrhage | |
| • bleeding within the brainSubarachnoid haemorrhage | ||
| • bleeding on the surface of the brain | ||
| Risk factors | General risk factors for cardiovascular disease | |
| • age | ||
| • hypertension | ||
| • smoking | ||
| • hyperlipidaemia | ||
| • diabetes mellitusRisk factors for cardioembolism | ||
| • atrial fibrillation | Risk factors | |
| • age | ||
| • hypertension | ||
| • arteriovenous malformation | ||
| • anticoagulation therapy |
| Site of the lesion | Associated effects |
|---|---|
| Anterior cerebral artery | Contralateral hemiparesis and sensory loss, lower extremity > upper |
| Middle cerebral artery | Contralateral hemiparesis and sensory loss, upper extremity > lower |
| Contralateral homonymous hemianopia | |
| Aphasia | |
| Posterior cerebral artery | Contralateral homonymous hemianopia with macular sparing |
| Visual agnosia | |
| Weber's syndrome (branches of the posterior cerebral artery that supply the midbrain) | Ipsilateral CN III palsy |
| Contralateral weakness of upper and lower extremity | |
| Posterior inferior cerebellar artery (lateral medullary syndrome, Wallenberg syndrome) | Ipsilateral: facial pain and temperature loss |
| Contralateral: limb/torso pain and temperature loss | |
| Ataxia, nystagmus | |
| Anterior inferior cerebellar artery (lateral pontine syndrome) | Symptoms are similar to Wallenberg's (see above), but: |
| Ipsilateral: facial paralysis and deafness | |
| Retinal/ophthalmic artery | Amaurosis fugax |
| Basilar artery | 'Locked-in' syndrome |
Lacunar strokes
Stroke may be defined as a clinical syndrome consisting of rapidly developing clinical signs of focal (at times global) disturbance of cerebral function caused by a vascular problem.
Features include: